1. Field of the Invention
The present invention relates to a position detecting sensor for application, for example, to an actuator or the like and which is capable of detecting a displacement amount.
2. Description of the Related Art
Heretofore, a position detecting sensor has been used for detecting a displacement position of a piston in an actuator or the like. The position detecting sensor, for example, is installed in an installation groove formed along an outer side surface of the actuator, and is equipped with a housing that is inserted into the installation groove, a detector disposed inside the housing, which is capable of detecting displacement of the piston, and a screw that is threaded into an end of the housing. The position detecting sensor is arranged in a movable manner along the installation groove via the housing.
More specifically, after the position detecting sensor is moved to a desired position along the installation groove corresponding to a detection position of the piston, an end of the screw abuts against a bottom side of the installation groove by threaded rotation of the screw, whereby the housing is pressed toward an inner wall surface of the installation groove. As a result, the position detecting sensor contained within the housing is fixed with respect to the installation groove under a pressing action against the inner wall surface of the installation groove. (See, for example, United States Patent Application Publication No. 2002/0014128).
However, according to the conventional technique disclosed in United States Patent Application Publication No. 2002/0014128, when the position detecting sensor is fixed with respect to the installation groove, such fixing occurs after the housing has been displaced within the installation groove in a direction that separates away from the piston. Therefore, the distance between the detector disposed internally within the housing and the piston, changes with respect to a preset distance that is set beforehand. In greater detail, the distance between the detector and the piston becomes greater than the preset distance. Stated another way, the relative positional relationship between the detector housing and the actuator changes, and therefore the detection accuracy of the piston position by the detector is lowered.
Further, when the position detecting sensor is fixed, the housing is pressed at an excessive force against the inner wall surface of the installation groove. Therefore, when the housing is formed from a resin material, there is a concern that the load applied to the position detecting sensor increases and durability of the sensor is lowered.